Perhaps there is a hobby that both of you love to do. You can use this 'theme' in your wedding invitations as well. If you both love to fish, you could use fishing line and lures for your invitations, or a hobby of wood_working could provide you with a way to expand your hobby into creating some special invitations. Regardless, if there is a hobby that the two of you share that helps to define you as a couple, don't be afraid to use it to your advantage and choose the best part of your hobby to direct your unique wedding invitation choices.
Boxed. Boxed wedding invitations are available at most retailers and provide a quick and easy alternative to other types of invitations. Also, they can be easily dressed up for a unique and personal touch. Note: Buy extras to ensure that you have enough in case of mistakes or you need to invite additional guests.